FSTAT

PROLOG

This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.

NAME

fstat
--- get file status

SYNOPSIS

DESCRIPTION

The
fstat()
function shall obtain information about an open file associated with
the file descriptor
fildes,
and shall write it to the area pointed to by
buf.
If
fildes
references a shared memory object, the implementation shall update in
the
stat
structure pointed to by the
buf
argument the
st_uid,
st_gid,
st_size,
and
st_mode
fields, and only the S_IRUSR, S_IWUSR, S_IRGRP, S_IWGRP, S_IROTH, and
S_IWOTH file permission bits need be valid.
The implementation may update other fields and flags.
If
fildes
references a typed memory object, the implementation shall update in
the
stat
structure pointed to by the
buf
argument the
st_uid,
st_gid,
st_size,
and
st_mode
fields, and only the S_IRUSR, S_IWUSR, S_IRGRP, S_IWGRP, S_IROTH, and
S_IWOTH file permission bits need be valid. The implementation
may update other fields and flags.
The
buf
argument is a pointer to a
stat
structure, as defined in
<sys/stat.h>,
into which information is placed concerning the file.
For all other file types defined in this volume of POSIX.1-2008, the structure members
st_mode,
st_ino,
st_dev,
st_uid,
st_gid,
st_atim,
st_ctim,
and
st_mtim
shall have meaningful values and the value of the
st_nlink
member shall be set to the number of links to the file.
An implementation that provides additional or alternative file access
control mechanisms may, under implementation-defined conditions,
cause
fstat()
to fail.
The
fstat()
function shall update any time-related fields (as described in the Base Definitions volume of POSIX.1-2008,
Section 4.8, File Times Update),
before writing into the
stat
structure.

RETURN VALUE

Upon successful completion, 0 shall be returned. Otherwise, -1 shall be
returned and
errno
set to indicate the error.

ERRORS

The
fstat()
function shall fail if:

EBADF

The
fildes
argument is not a valid file descriptor.

EIO

An I/O error occurred while reading from the file system.

EOVERFLOW

The file size in bytes or the number of blocks allocated to the file or
the file serial number cannot be represented correctly in the structure
pointed to by
buf.
The
fstat()
function may fail if:

EOVERFLOW

One of the values is too large to store into the structure pointed to
by the
buf
argument.

The following sections are informative.

EXAMPLES

Obtaining File Status Information

The following example shows how to obtain file status information for a
file named
/home/cnd/mod1.
The structure variable
buffer
is defined for the
stat
structure. The
/home/cnd/mod1
file is opened with read/write privileges and is passed to the open
file descriptor
fildes.

APPLICATION USAGE

RATIONALE

FUTURE DIRECTIONS

SEE ALSO

COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.unix.org/online.html .